Hitachi NEXT Series Service Manual

12
2.3.3 Capacity Control System
Air-Cooled Water-Cooled
Air intake
Air Intake filter
1st-stage
airend
Intercooler
Check valve
Aftercooler
Blowoff
silencer
Pressure sensor
Air
discharge
1st-stage blowoff solenoid valve (1)
2nd-stage blowoff solenoid valve (1)
2nd-stage blowoff solenoid valve (2)
1st-stage blowoff solenoid valve (2)
2nd-stage
airend
PS2
Purging Air Flow and Action of Blowoff Solenoid Valve
Operation phase
Blowoff solenoid
valve (1)
Blowoff solenoid
valve (2)
Starting Fully opened Fully closed
Loading Fully closed Fully closed
Purging Fully opened Fully closed
Stop Fully opened Fully opened
Power Interruption Fully closed Fully opened
■ Relationship between Air Consumption Rate and Capacity Control System
※ The value in ( ) is indicated for water-cooled type.
Model
Rated
pressure
psi [MPa]
Air
consumption
(%)
Operating
frequency (Hz)
Capacity control system
Pressure setting
psi [MPa]
Capacity
control type
Initial
Example
of Lower
55 kW
125 [0.86]
100 - 75 (65) 134 (136) - 108 (108)
① CPCS motor
speed control
Control
pressure
125 [0.86] 120 [0.83]
AUTO ON
VSDA
or
AUTO OFF
VSDB
75 kW
100 - 60 (50) 133 (137) - 80 (72)
55 kW
125 [0.86]
75 (65) - 5 82
②
Two-step purge
control
Cut-out
pressure
138 [0.95] 125 [0.86]
AUTO ON
VSDA
or
AUTO OFF
VSDB
75 kW
60 (50) - 5 66 (60)
Cut-in
pressure
131 [0.90] 120 [0.83]
All
model
125 [0.86] 5 - 0
Main motor stop
③ Motor stop/
restart control
Cut-in
pressure
131 [0.90] 120 [0.83]
AUTO ON
VSDA
The air compressor supports the three (3) capacity control systems as shown above.
Depending on the varying air consumption, an appropriate system is automatically selected. For more information, see
the following page. Operation frequency is shown by Digital monitor. LCD monitor displays up to first figure after
decimal place.

Hitachi NEXT Series Specifications

General

Brand	Hitachi
Model	NEXT Series
Category	Air Compressor
Language	English